A man threw a homemade explosive device into the Cheesecake Factory in Pasadena, setting off an explosion that sent frightened diners fleeing but caused no serious injuries, officials said.

The incident happened at the restaurant in Old Town Pasadena just after 6 p.m. Witnesses said a man tossed a device into the restaurant and ran from the scene. It detonated and gave off heavy smoke, but no one was injured.

The suspect was described as about 6 feet tall with a thin build and a heavy beard. He was wearing all black clothing and a black beanie.

The Los Angeles County Sheriff's Department bomb squad responded and rendered the device and restaurant safe. Pasadena police are investigating and as a precaution have also contacted the FBI.

The Cheesecake Factory released a statement: "This evening an incendiary device exploded within our Pasadena restaurant. Thankfully, none of our guests or staff was injured. Law enforcement is actively investigating the incident and we hope to reopen in Pasadena on Friday, as usual."

Anyone with information is asked to call Pasadena Police at (626)744-4241.